GA4000 · 7 documented thickness rows
Celotex U-value calculator
The product searched as Celotex GA4000 is now presented in current source material as SOPRATHERM GA4000. This calculator uses the linked technical sheet for seven thicknesses and keeps that naming change explicit.
Element surfaces and correction
The element label sets only the displayed surface-resistance pair. An exposed floor is not a ground-coupled floor calculation. Use Custom when the boundary conditions differ.
Assembly result
Effective R m²K/W
Layer R before bridge correction · m²K/W
Illustrative starting layers, not an approved specification. One repeating timber layer only. No metal frames, ground-coupled floors or automatic fixing/gap corrections. A U-value alone does not establish compliance.
Saved comparisons
| Assembly | U (W/m²K) | Actions |
|---|
Calculation ledger
| Layer | Thickness (mm) | λ (W/mK) | Calculated R (m²K/W) | Declared R (m²K/W) |
|---|
Fixed R has no implied thickness or conductivity. All intermediate calculations retain full precision; display values are rounded.
Source-linked comparison
Celotex / SOPRATHERM product data
Select a documented GA4000 thickness, add the rest of the roof, lining or floor build-up, and compare the whole-assembly result. Product naming and source conflicts are disclosed rather than silently normalised.
Checked · Version 2026-08-29.1 · Selected UK product literature, not live stock or a complete manufacturer catalogue.
What the dataset lets you decide
- Seven documented thicknesses from 50 to 100 mm use declared conductivity 0.022 W/mK.
- The technical sheet controls the published rows and lists 100 mm at declared R 4.50 m²K/W.
- A captured product-page value conflicted with that technical sheet; the conflicting value is not used.
Manufacturer property facts remain attributed to their linked sources. Inzonex supplies the selection, calculation, chart and reusable exports.
All 7 source-linked rows
| Product | Documented use | mm | λ (W/mK) | Declared R | Calculated R | References |
|---|---|---|---|---|---|---|
| SOPRATHERM GA4000 (previously Celotex) | Pitched roof, dry lining and floor | 50 | 0.022 | 2.25 | 2.273 | Property · range/use |
| SOPRATHERM GA4000 (previously Celotex) | Pitched roof, dry lining and floor | 60 | 0.022 | 2.70 | 2.727 | Property · range/use |
| SOPRATHERM GA4000 (previously Celotex) | Pitched roof, dry lining and floor | 70 | 0.022 | 3.15 | 3.182 | Property · range/use |
| SOPRATHERM GA4000 (previously Celotex) | Pitched roof, dry lining and floor | 75 | 0.022 | 3.40 | 3.409 | Property · range/use |
| SOPRATHERM GA4000 (previously Celotex) | Pitched roof, dry lining and floor | 80 | 0.022 | 3.60 | 3.636 | Property · range/use |
| SOPRATHERM GA4000 (previously Celotex) | Pitched roof, dry lining and floor | 90 | 0.022 | 4.05 | 4.091 | Property · range/use |
| SOPRATHERM GA4000 (previously Celotex) | Pitched roof, dry lining and floor | 100 | 0.022 | 4.50 | 4.545 | Property · range/use |
U-value, without hidden layers
1. Resistance in series
R_total = Rsi + ΣR_layer + Rse
U = 1 / R_total + ΔU
Thickness is entered in millimetres and converted to metres. A known-R layer accepts a separately established resistance, not a guessed cavity thickness. Surface presets use 0.10, 0.13 or 0.17 inside and 0.04 outside for the identified exposed-air cases. Other conditions need appropriate inputs.
The browser calculation is checked against the open-source ht plane-conduction reference. This is a building-layer calculation, separate from the industrial pipe tool's lumped heat-transfer coefficient.
2. One repeating timber bridge
R_lower = Rsi + ΣR_equivalent + Rse
R_effective = (R_upper + R_lower) / 2
The timber fraction is the fraction of this layer's area occupied by timber, not the fraction of the whole building. For the bridged layer, R_equivalent = 1 / [(1−f)/R_layer + f/R_bridge]. The tool stops above an upper/lower ratio of 1.5. It does not model metal framing, crossing bridges or junction ψ-values.
Both worked presets reproduce SEAI's Irish roof examples. The rafter case has R limits about 6.36 / 5.78; the ceiling case about 6.438 / 6.221, with an explicit 0.0014 W/m²K loft-hatch correction. These are examples, not UK regulatory defaults.
What this result does not decide
Actual moisture, temperature, workmanship, fixings, ventilation and junctions can change performance. This tool does not select a regulatory target, assess condensation or fire safety, verify a product's application or predict annual bills. Ground-coupled and suspended ground-floor calculations require their own geometry and boundary methods. The outside surface setting is editable because sheltered and ventilated conditions differ.
Sources and method references
- Kingspan Thermapitch TP10 GB brochure, page 5
- SOPRATHERM GA4000 technical data sheet TDS-UK-INSUK0025.a/EN
- Soprema: GA4000, previously Celotex
- ROCKWOOL Flexi technical sheet, November 2025, page 3
- ROCKWOOL Flexi UK listed product variants
- Kingspan Kooltherm K108 UK Declaration of Performance 1000.UKDoP.K108.003
- Kingspan Kooltherm K108 Cavity Board UK product page
- Recticel Eurowall+ UK technical datasheet 6VICBX7DDFHZ 230703
- Recticel Eurowall+ UK product specifications
- SEAI DEAP guidance, pages 76-79: worked roof examples
- UK government moisture research, modelling surfaces, page 12
- Santos et al., Energies 2020, section 2.1.1: combined method and limits
- ht conduction library: k_to_R
Celotex / SOPRATHERM U-value questions
Why does the page say SOPRATHERM as well as Celotex?
The current manufacturer page identifies GA4000 as SOPRATHERM GA4000 and notes the previous Celotex name. The page retains Celotex in the heading because that is the product name people still search, while the dataset uses the current source identity.
Which GA4000 thicknesses are included?
The source-linked table includes 50, 60, 70, 75, 80, 90 and 100 mm rows. The tool does not interpolate unlisted product thicknesses.
Which 100 mm resistance value does the tool use?
The linked technical sheet lists declared R 4.50 m²K/W at 100 mm, and that is the retained declared value. The calculator also shows thickness divided by conductivity, about 4.545 m²K/W, so the rounding difference is visible.
Does this page certify a Celotex or SOPRATHERM build-up?
No. It is an independent Inzonex calculator using attributed product facts. It is not manufacturer-endorsed and does not replace project-specific condensation, fire, junction or regulatory assessment.